Bearing for the shafts of delicate instruments.



J. JOHNSON. BEARING-TOR THE SHAI'TS 0F DBLIOATE INSTRUMENTS.

APPLIOATION FILED AUG. 24. 1904.

Patented June 1,1909.

FigL.

Irv/ember; Joseph Johnson o uzy asses:

' JOSEPH Johnson", OF LYNN-MASSACHUSETTS, AQSSIGNOR TOGENERAL n nuornro COMPANY,

. AQORPORATION OFNEW; YORK i l vj BEARING roRfrHEsHAFT'sor DELIGATE INsTRmri'rs.

I n 923,191, r,

: 1b all whom "it may concern:

citizen of th'e United States, residing at Lynn, county of Essex, State of Massachu- "setts; have invented certain new and useful Improvements in Bearings for-the Shafts of "Delicate-Instruments, of which the following H is a Specification.

i The shafts of instruments of this type have This invention relates to bearings for the shafts of elicate instruments, such for 1n stance as electrical measuring instruments.

' commonly been rovided with tapered ends,

- and jewels have can mounted in the instrument in proper relation to support the shaft.

, Thesejewels are usuallysapphires and have been commonly provided with cups or depressions which receivethe ends of the shaft. In orderthat the shaft of the-instrument may amount of end play be allowed the shaft On account ofthe extreme hardness of a sap- The object ofmy invention is to provide jewel bearings for'the shaft ofa delicate-in- I strument which shall hold the shaft against mit the amount of axial movement required lateral movement, andat the same time perfor easy working. I accomplish this by pror viding a smallopening in or through one or both of the jewels fromthe bottom of the ta- 'pering recess or depression. This opening in the jewel can be readily madeby drilling. The-shaft of the instrument is provided with a tapered end the point of which extends.

into the: opening extending ;v through thejewel.- In this way when the jewels are so positioneclfias to permit the necessary amount of end playthe lateral movement of the shaft one-hundredth of an inch in diameter and- The novel features of-my invention"will be definitely indicated in the: claims appended hereto. I

The details of'construction and the mode "of-operation of an instrument rovided with my 1m roved bearings will be etter understood y reference to the {following descrip- Specification of Letters Patent.

' Application filed August 24; 1904. serial'No. 221,928.

move'freely 'it is necessary thata certain rounded ends of thetapered depressions inv the jewels.

these" arts of the instrument-is not con- '7 v "Patented (lune 1,1909,

tion taken in connection with the accompanying drawings which show the preferred embodiment of'my invention. A 4

In the drawings,. Figure 1 is an elevation broken away in part of an electrical measuring instrument provided with my improved bearings; Fig. '2 is an enlarged'section of: the

upper Lbearing'; Fig. 3 is an enlarged view showing the relation of the shaft and beermgs; v s In-the drawings, Fig. 1 shows anielectf'cal'f measuring instrument of a standardfty well known to users of-electrie'al' ap a i i It is provided with a base. 1on ported a frame 2' which carries a coil 3 inclined at an angle of grees tothe-shaft 4 which ismoii'nted-ini earings carried by arms 5, j-5. integral the frame 2. Within coil 3 and mounted ontl e shaft 4 is .a magnetic element which isaicted upon by the coil tomove theshaft its bearings. Shaft 4'carri'es-an indeifff which moves back and'forth over' ascale mounted within. the instrument. under a glass plate.

Secured on the upperarm -5 a bracket 7 to which is secure 'oneend ofa; light spi ifa'l spring- 8, the otheren'd ofwh'ich is secured to shaft 4 sothat tliespringj'S. furnishes the} zero-seeking, force for the. index, 011 the shaft 4 is a disk Q'WI'iich-isgTa'sped by'springicl'amp's 10 to hold theQs'haft hr'mly. and-re have the jewel bearings from the weight of the movableelement when the instrument is not in use. A more detaileddescription of M sidere necessary. as they form no part of, my present invention. I

In each of the arms 55 of frame 2' is a threaded opening inwhich is secured a j ewelpost 11 he in place by 'a lock'nut:12,-and seated in the end of each of the jewel-posts '11 is a jewel 13 provided with a V-shaped depression therein. The jewel 13': for the upper hearing has a small hole drilled there through to the bottom of the V shaped d'egression as shown at the to of Fig.;3;ithis olelis very small, preferably less; than one its walls intersect thepolished surfaces of the V-shaped depression at an angle different 'from the angle between the shaftand the bearing surface of the "taperedtipof the shaft, causing the j ewelto make atcthe edge very short distance from the end of the shaft. 3 which are designed for use with their shafts The jewel i thelower bearing may have a openmg drilled theretlirough if des'ired, though I prefer to cut in the jewel for 5 the lower bearing a V-shaped depression tapering to as sharp a point as possible but without an; opening through it. The. ends -tof the'shaft t ofthe instrument are tapered :bff'to sharp points andthelower end rests in gthe bottom of the depression inlthe jewel formingggthe lower bearing block and Y the uppenenfl'extends' a very short distance into the opening drilled'through the jewel formtheupper bearing block so that the upper end of the-shaft is supported a short distance ielo'w the point;

- flhe advantagelof the--construction herein and described-is obvious. .In the usual -;'of bearing the jewels have V-shaped or depressions cut therein but the sides fify thejse depressions do not extend straight -to form a sharp point at the-bottom of pitch cup. As above pointed out, it is neces- 5 5. 3m provide for a small amount of axial 2,5 movement of the shaft of the instrument in :order that it will move freely in response to B "htvariations of the actuating force.

{With the .usual type of bearings, adjustment which allows this end movement permits a considerable amount of lateral movement of shaftwhich is very objectionable and {which not only, affects the accuracy of the indications, but also renders greater clear-- ances necessary for the moving parts thereby greatly reducing the sensitiveness ofthe inlstrument. v hen the upper bearing is constructed as shown in Fig. 3 and the samearnount of end play is permitted as with the usual type of bearing the amount of lateral movement permitted is very small.

The construction herein shown and describedis particularly'useful in instruments in a vertical position. In such cases I prefer to provide an opening through. the jewel forming the upper bearing only. However, I do not wish'to be understood as limited to any particular class ofinstruments or to instrumentsin which only one of the bearing blocks is provided with an opening therethrough. Also it is obvious that this opening-in the jewel at the bottom of the cup o'rdepression therein need not extend entirely through it as shown herein; it may, extend into the jewel only far enough to clear the point of the shaft.

greater than the angle at the tipof the shaft anda cylindrical hole at the bottom of said depression for receiving the tip of the tapered shaft 2. In a measuring instrument, thecom JOSEPH JOHNSON.

' 'Witnessesz.

JOHN A. McMANUs, Jr,

GEORGE W. BEADLE. 

